CVE-2026-77696

Issue summary: SM2 signature generation uses non-constant-time arithmetic on secret values, forming a timing side-channel. Impact summary: An attacker able to measure SM2 signing times may learn information about the per-signature secret nonce, which over many signatures can, via a lattice / Hidden Number Problem attack, lead to recovery of the private key. CWE: CWE-208: Observable Timing Discrepancy Description: SM2 signature generation computes the signature value using variable-time BIGNUM operations on the secret nonce and the private key, so the time taken to produce an SM2 signature depends on these secret values, forming a timing side-channel. Applications performing SM2 signature generation are affected on all platforms. FIPS Impact: no SM2 is not a FIPS algorithm.

• openssl openssl (>= 1.1.1 < 1.1.1zj) • openssl openssl (>= 3.0.0 < 3.0.23) • openssl openssl (>= 3.4.0 < 3.4.8) • openssl openssl (>= 3.5.0 < 3.5.9) • openssl openssl (>= 3.6.0 < 3.6.5) • openssl openssl (>= 4.0.0 < 4.0.3)